1. Field of the Invention
The present invention relates to the simulation of jet engine noise and more particularly to a circuit for generating pseudo-random noise with arbitrarily long repetition rates.
2. Description of the Prior Art
There are several known devices for simulating jet engine noise. Mayer et al, U.S. Pat. No. 4,314,236, teaches production of a variety of audio sound effects by utilizing a variable digital noise generator driven by a variable clock, the audio output is shaped by either selectively ANDing the outputs or by gated resistive summing of the output signals. U.S. Pat. No. 4,296,384 to Mishima teaches the use of a single pseudo-random pulse generator, which is clock driven, in combination with a bandwidth designating circuit and means for converting the digital output of the generator to an analog signal. U.S. Pat. Nos. 4,023,078 and 3,831,172 to Olliges et al disclose a circuit for simulating jet engine noise which utilizes a single random noise generator which in turn is coupled to a modulating circuit. U.S. Pat. No. 3,718,987 to Carver teaches the use of two voltage controlled rectifiers for simulation of jet engine whine. The voltage controlled oscillators have slightly different frequencies and are summed in a resistive circuit to obtain a signal which contains all of the desired harmonics.
None of the known prior art devices provides for simulating jet engine noise with arbitrarily long repetition rates which are required for realism. This realism in jet engine noise is required in apparatus used to trigger anti-aircraft bombs planted on runways and for deception of sensors used for simulators.